Negative touch recovery for mutual capacitance scanning systems
First Claim
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1. A mobile communication device, comprising:
- a touch-sensitive surface having a circuit configured for;
storing running baseline capacitance measurements and initial baseline capacitance measurements for a plurality of touch sensors of the touch-sensitive surface;
repeatedly taking capacitance measurements from the touch sensors during device operation, counting a number of positive transitions of the measurements, and counting a number of negative transitions of the measurements, wherein each positive transition includes capacitance measurements exceeding the stored initial baseline measurements by a predetermined first threshold amount, each negative transition includes capacitance measurements falling below the stored initial baseline measurements by a predetermined second threshold amount, and the predetermined first and second threshold amounts are specified independently;
determining that the count of negative transitions differs from the count of positive transitions by a predetermined amount; and
in response to determining that the count of negative transitions differs from the count of positive transitions by the predetermined amount, re-initializing the stored initial baseline capacitance measurements.
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Abstract
A device stores running baseline measurements and initial baseline measurements for a plurality of touch sensors. The device repeatedly takes measurements from the touch sensors during device operation, and counts a number of positive transitions of the measurements, and counts a number of negative transitions of the measurements, the transitions relative to the stored initial baseline measurements. The device re-initializes the stored initial baseline measurements if and only if the count of negative transitions differs from the count of positive transitions by a predetermined amount (a “negative touch state”).
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Citations
19 Claims
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1. A mobile communication device, comprising:
a touch-sensitive surface having a circuit configured for; storing running baseline capacitance measurements and initial baseline capacitance measurements for a plurality of touch sensors of the touch-sensitive surface; repeatedly taking capacitance measurements from the touch sensors during device operation, counting a number of positive transitions of the measurements, and counting a number of negative transitions of the measurements, wherein each positive transition includes capacitance measurements exceeding the stored initial baseline measurements by a predetermined first threshold amount, each negative transition includes capacitance measurements falling below the stored initial baseline measurements by a predetermined second threshold amount, and the predetermined first and second threshold amounts are specified independently; determining that the count of negative transitions differs from the count of positive transitions by a predetermined amount; and in response to determining that the count of negative transitions differs from the count of positive transitions by the predetermined amount, re-initializing the stored initial baseline capacitance measurements. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A device comprising a touch-sensitive surface having a circuit configured for:
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storing running baseline capacitance measurements and initial baseline capacitance measurements for a plurality of touch sensors; repeatedly taking capacitance measurements from the touch sensors during device operation, counting a number of positive transitions of the measurements, and counting a number of negative transitions of the measurements, wherein each positive transition includes capacitance measurements exceeding the stored initial baseline measurements by a predetermined first threshold amount, each negative transition includes capacitance measurements falling below the stored initial baseline capacitance measurements by a predetermined second threshold amount, and the predetermined first and second threshold amounts are specified independently; and detecting a negative touch state in which the count of negative transitions differs from the count of positive transitions by a predetermined amount; and in response to detecting the negative touch state, re-initializing the stored initial baseline capacitance measurements. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method performed at a touch-sensitive device with a plurality of touch sensors, comprising:
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upon transitioning the touch-sensitive device from a sleep state to an active state, scanning the plurality of touch sensors to establish baseline capacitance measurements; after transitioning the touch-sensitive device from the sleep state to the active state; storing running baseline capacitance measurements and initial baseline capacitance measurements for the plurality of touch sensors; repeatedly taking capacitance measurements from the touch sensors during operation of the touch-sensitive device, counting a number of positive transitions of the capacitance measurements, and counting a number of negative transitions of the capacitance measurements, wherein each positive transition includes capacitance measurements exceeding the stored initial baseline capacitance measurements by a predetermined first threshold amount, each negative transition includes capacitance measurements falling below the stored initial baseline capacitance measurements by a predetermined second threshold amount, and the first and second threshold amounts are asymmetrical; determining that the count of negative transitions differs from the count of positive transitions by a predetermined amount; and in response to determining that the count of negative transitions differs from the count of positive transitions by a predetermined amount, re-initializing the stored initial baseline capacitance measurements. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification